Residual-moveout analysis in presence of strong lateral velocity anomalies

Residual-moveout analysis in presence of strong lateral velocity anomalies

Biondo Biondi

Biondo Biondi

Biondo Biondi

Abstract:

The analysis of a simple synthetic data set recorded above a strong velocity anomaly and a flat reflector illustrates the challenges that can be encountered when performing residual-moveout analysis using a family of curves described by a single parameter. Overcoming these challenges is important if we want to use automatic velocity analysis methods that rely on the derivative of the stack power with respect to the residual-moveout parameter to compute velocity gradients. My analysis shows how, at some reflector locations, the stack-power may have a poorly defined peak because the residual moveout is more complex than the one-parameter model assumes. At other reflector locations, the peak of the stack-power is sharp but it is too far from the value of the parameter corresponding to no residual moveout. Consequently, the derivatives are unreliable, and possibly have even the wrong sign. More robust information could be provided by migrating data with lower frequencies, when available. A more general solution is smoothing the stack power along the residual-moveout parameter before evaluating its derivatives.

Residual-moveout analysis in presence of strong lateral velocity anomalies